[AG and RS channel tuning] Add thread work threshold to tuning models and precompute reg index in LL128 (#1641)

* Update LL128 elems per thread

* Precompute ix[g] in LL128 prim

* Make Threadthreshold part of tuning models

* Ignore channel tuning when channels are env controlled

* Tune LL128 max limit for AG

* Tune LL128 max limit for RS

* Retune AR LL128 limits due to changes

* Update CHANGELOG.md

---------

Co-authored-by: Jeffrey Novotny <jnovotny@amd.com>

[ROCm/rccl commit: 00c1eb098c]

projects/rccl/src/include/rccl_common.h

@@ -33,10 +33,11 @@ typedef enum RcclTunableColls {
 } rcclTunableIndex_t;
 
 #define RCCL_LL_LIMITS_UNDEFINED 0
-#define RCCL_PROTOCOL_ENTRY_SIZE 3
+#define RCCL_PROTOCOL_ENTRY_SIZE 4
 #define RCCL_PROTOCOL_MIN_IDX 0
 #define RCCL_PROTOCOL_MAX_IDX 1
 #define RCCL_PROTOCOL_FACTOR_IDX 2
+#define RCCL_PROTOCOL_THREAD_THRESHOLD_IDX 3
 
 #ifdef RCCL_EXPOSE_STATIC
 #define RCCL_STATIC_EXPOSE_CHECK()
@@ -71,8 +72,7 @@ inline size_t rcclGetSizePerRank(ncclFunc_t const& func, size_t const& nBytes, i
   return (func == ncclFuncReduceScatter || func == ncclFuncAllGather) ? nBytes / nRanks : nBytes;
 }
 void rcclUpdateCollectiveProtocol(struct ncclComm* comm, size_t const& nBytes, struct ncclTaskColl* info);
-
-
+void rcclUpdateThreadThreshold(struct ncclComm* comm, size_t const& nBytes, struct ncclTaskColl* info, int& threadThreshold);
 ncclResult_t rcclGetAlgoInfo(struct ncclComm* comm, ncclFunc_t coll, uint64_t count, ncclDataType_t dataType,
                              int collNetSupport, int nvlsSupport, int numPipeOps,
                              int* algo, int* protocol, int* maxChannels);